The present invention relates to the oxidation of hydrocarbons. More specifically, the present invention relates to the oxidation of hydrocarbon waxes and petrolatums. Oxidized petroleum fractions including waxes and petrolatums have, in the past, been employed as the source of saponifiable material in the production of lubricating greases and in the formulation of protective coatings. The oxidates employed for these purposes have been obtained by oxidizing selected petroleum fractions under controlled conditions such that the oxidation proceeds only to a limited extent.
Oxidation of petroleum fractions by the above-described method had, associated with it, certain difficulties. Some petroleum fractions are not easily oxidized by the prior art processes and even though oxidizable, in some instances, require a preliminary induction period before the rate of oxidation becomes appreciable. Another problem associated with oxidizing petrolatums is the discoloration of the final wax product rendering it aesthetically unattractive for use in some formulations.
Other problems involve the presence of various oxidation inhibitors in the hydrocarbon fraction. These oxidation inhibitors are often nitrogen and/or sulfur-containing compounds present as impurities in the hydrocarbon source.
To overcome the above problems, the prior art suggests the employment of various oxidation catalysts, such as redox catalysts with or without promoters, for use in the hydrocarbon oxidation process. The redox catalysts are often based on expensive redox metals, such as manganese, chromium and the like.
U.S. Pat. No. 2,410,642 to Farkas et al. discloses the partial oxidation of either a narrow boiling point low molecular weight hydrocarbon fraction or a single hydrocarbon to prepare predominantly alcohols and ketones. As catalysts, this reference teaches the use of metals of atomic number 20 to 30, that is, redox metal catalysts. Calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, magnesium, aluminum, molybdenum, silver, tin, tantalum and uranium metals are recited, which can be provided by the free metal or metallic salts such as the metal nitrates, sulfates, sulfites, phosphates, phosphites, etc. The narrow hydrocarbon range and single hydrocarbon feeds contemplated by Farkas et al are those which are oxidizable in the absence of the metal catalyst.
U.S. Pat. No. 2,424,671 to Staussel discloses the reaction of oxygen compounds of chlorine with mercaptans in tank bottoms to convert the mercaptans to oxygen promoters, prior to an air oxidation step.
U.S. Pat. No. 2,472,152 to Farkas et al. discloses the partial oxidation of diesel engine fuel with oxidizing agents such as aqueous solutions of oxyhalogen acids.